Steering and Differential Braking for High-Speed Obstacle Avoidance
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Solution Overview
Problem
Existing driver assistance systems, such as automatic emergency braking and evasive steering, struggle to effectively prevent collisions at high speeds and maintain vehicle controllability and stability during obstacle avoidance maneuvers, particularly when the vehicle is traveling at high speeds and obstacles are in adjacent lanes.
Innovation Solution
A system and method that integrates steering and differential braking systems, using a parameter (αDB) to manage their simultaneous control, ensuring controllability constraints are met by limiting steering torque and stability constraints by bounding slip and yaw rate, with a feed-forward controller to compensate for trajectory errors, and a closed-loop controller to maintain vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If automatic emergency braking system is used to prevent collision, then collision prevention is improved, but effectiveness deteriorates when vehicle is traveling at high speed and another vehicle is behind it
Solution Approach 1:
The system dynamically switches between braking-only mode and combined steering-braking mode based on real-time assessment of maneuverability constraints and vehicle state. The controller adjusts the mixing parameter alpha continuously, transitioning from pure braking (alpha=0) to combined maneuvers (alpha>0) when high-speed avoidance is detected, enabling the system to adapt to high-speed scenarios while maintaining collision prevention effectiveness
Solution Approach 2:
The control system integrates multiple functions into a single unified controller that can perform both automatic emergency braking and automatic evasive steering. By incorporating both steering torque control and differential braking control in one system with a unified decision-making algorithm, the system achieves multi-functionality that allows it to handle both low-speed braking scenarios and high-speed steering-braking combined scenarios
2Adaptability or versatility
If differential steering/braking system is activated for lane change avoidance, then avoidance capability is improved, but vehicle controllability and stability deteriorate due to excessive torque demand
Solution Approach 1:
The system introduces a mixing parameter alpha that continuously varies between 0 and 1 to adjust the contribution of differential braking to the total avoidance torque. By dynamically changing this parameter based on real-time vehicle state and constraint satisfaction, the system optimizes the balance between avoidance effectiveness and controllability, preventing excessive torque demand while maintaining maneuver capability
Solution Approach 2:
The controller continuously monitors vehicle state variables including lateral acceleration, yaw rate, and steering angle, and uses this feedback to adjust the mixing parameter alpha in real-time. The constraint satisfaction algorithm provides feedback on whether current maneuvers violate controllability or stability constraints, allowing the system to adaptively reduce torque demand when limits are approached while maintaining avoidance effectiveness
3Adaptability or versatility
If steering system is used for obstacle avoidance, then avoidance maneuver is improved, but vehicle stability deteriorates at high speed
Solution Approach 1:
The system merges steering control and differential braking control into a unified combined maneuver control strategy. By coordinating both actuators simultaneously with a unified control law that accounts for their complementary effects, the system achieves both effective avoidance maneuvering and enhanced vehicle stability at high speeds, overcoming the limitations of using either system alone
4Reliability
If torque demand from electric power steering is limited to ensure driver control, then driver safety is improved, but avoidance trajectory accuracy deteriorates
Solution Approach 1:
The differential braking system acts as an intermediary that supplements the steering system when torque demand approaches limits. By coordinating differential braking torque with steering torque, the system achieves the required avoidance trajectory while keeping steering torque within safe limits that preserve driver control, effectively using braking as a mediator to bridge the gap between safety constraints and trajectory accuracy requirements
Data Source
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AI summary
The invention relates to a method (30) for obstacle avoidance, involving: - detecting an obstacle (1) in the vicinity of a motor vehicle (1) and planning a trajectory for avoiding said obstacle, and - controlling steering systems (power steering) and/or differential braking systems configured to manage said avoidance trajectory.